Comparison of the radiation spectrum (top panel) and electron distribution (bottom panel) at t = 0.1 s from Fig. 5 (black solid line) to four cases where the value of one parameter is changed at a time. In two simulations, the wind density is decreased by a factor of 10 (red dashed line) and 100 (blue dashed line) from the fiducial value. In the other two cases, the magnetic energy fraction is decreased by a factor of 10² (red dash-dot line) and 10⁴ (blue dash-dot line).